1. Field of the Invention
The invention relates to a method for displaying calling party information in a network telephone system that can access a public telephone network, a digital public telephone network, or the like via a communication network such as a LAN. The invention also relates to a network telephone system, a gateway apparatus, and an information terminal.
2. Description of the Related Art
It is known to provide a telephone communication system that accesses a public telephone network or a digital public telephone network, or even a closed telephone network such as a leased line network within a private organization, via a communication network constructed as a LAN (Local Area Network) within a building or the like.
Traditionally, certain types of telephones connected to a public telephone network or a digital public telephone network have been equipped with a function to display, upon arrival of an incoming call, the calling telephone number information of which the called party is notified through a calling number display service. Telephones of the type that displays information such as the caller's name by searching internally stored telephone directory data based on the received calling telephone number information have also been commercially implemented. There has also been implemented a telephone communication system in which incoming calls from an external public network can be routed to particular one or more telephones by means of a gateway apparatus or a private branch exchange (PBX) accommodated in a communication network constructed within a building or the like.
Japanese Unexamined Patent Publication JP-A 2001-156906 (2001) proposes a method in which, when a call arrives to a wireless communication terminal connected to a PHS (Personal Handyphone System) network, a mobile telephone network, or the like, the calling telephone number information received at that time is also transmitted to another information processing apparatus by using a short-range wireless communication technology, to display the calling telephone number information along with a message indicating the arrival of a call. This prior art method is intended to provide a reliable indication of an incoming call and an identification of the identity of the caller even when the wireless communication terminal such as a mobile telephone is set to a ringer-off mode or a vibration or like operation mode.
Generally, in the case of a wired telephone, unlike a portable wireless telephone such as a PHS or a mobile telephone, even when the telephone terminal is equipped with a calling party information display function, if a user is at some distance away from the telephone at the time of the arrival of a call, the user is unable to check the calling telephone number information and, depending on the situation, even the ringing tone cannot be heard. If the connected telephone does not have means for displaying the calling telephone number information, there is no way of checking the calling party. Further, in the case of a telephone terminal that also displays the caller's name by searching an internally stored telephone directory based on the received calling telephone number information, even when a personal information database such as an address book is stored in a PDA (Personal Digital Assistant) terminal that is usually carried by the user, the user has to re-enter the personal information into the telephone terminal if the calling party information is to be displayed on the telephone terminal. Hence, there is a problem that cumbersome entering operation is required and its availability is poor.
Here, there are cases where the personal information entered into the telephone terminal can also be used as a telephone directory for making outgoing calls. On the other hand, in Japanese Unexamined Patent Publication JP-A 6-46120 (1994), there is proposed a method that automatically makes a call by retrieving the desired telephone number from internally stored telephone directory data by operating an electronic organizer having a telephone directory function. In this case, entering the personal information into the telephone terminal is necessary only for having the calling telephone number information displayed.